Pump compensator

ABSTRACT

A pressure compensated variable displacement pump. The pump comprises a vane assembly positioned within a housing and a pressure ring positioned around the vane assembly to float within the housing. Additionally, the pump comprises a compensator having a guide, a first end, a second end and a plurality of individual adjusting elements. The second end is in contact with the pressure ring wherein the plurality of adjusting elements is positioned adjacent the second end in series to vary pressure created by the vane assembly against the pressure ring. A method of varying pressure comprises rotating a vane assembly within a pump housing and applying high pressure from the vane assembly against a pressure ring. Next, the method comprises varying the pressure by biasing a plurality of adjusting elements to reciprocate a guide against the pressure ring.

BACKGROUND OF THE INVENTION

The present invention relates to a pump. In particular, the presentinvention relates to a pressure compensated variable displacement pumpwhich can operate at high pressures.

Positive displacement pumps capture fluid in a chamber and reduce thevolume in the chamber to force the fluid from the pump. Fluid pumpscreate flow while operating on a displacement principle wherein fluidenters an input and displaces to an output via the pump. Fixeddisplacement pumps discharge fluid in a continuous flow while variablevolume pumps discharge fluid in a non-continuous flow, i.e. periods withno discharge.

Positive-displacement pumps deliver a definite volume of fluid for eachpump cycle operation, regardless of resistance, so long as the pumpcapacity is not exceeded. If an outlet is closed or exceeds the outputpressure, the pump drive will stall or the pump will experiencebreakdown. Accordingly, positive-displacement pumps require a pressureregulator or pressure relief valve.

Pumps are rated according to the volumetric output which is the amountof liquid that a pump can deliver to the outlet per unit of time at agiven drive speed. The volumetric output is usually expressed in gallonsper minute. Since the pump drive affects volumetric output, pumps arealso rated by displacement.

Displacement is the amount of fluid transferred from a pump's inlet tothe pump's outlet in one cycle wherein displacement is either fixed orvariable. In fixed displacement, the output can be changed only byvarying the drive speed. In variable displacement, the output can bechanged by regulating the pressure control and/or changing the drivespeed.

A typical positive variable displacement pump is a vane pump. Vane pumpsuse a slotted rotor which rotates within a housing driven by a driveshaft. Vanes slide within the rotor in an expanding configuration fromthe rotor to push the fluid from the inlet to the outlet. Typically, thevanes are positioned within the slots of the rotor. As the rotor turns,the vanes are thrown outward by a combination of hydraulic pressure andcentrifugal force which holds the vanes in contact with a pressure ringwhich surrounds the rotor/vanes. The ring is offset by the pressure ofthe pressure regulator used to control maximum system pressure.

Vane pumps are typically compact in design and provide excellenthorsepower to weight ratios while offering high volumetric efficiencies,good suction characteristics and low noise generation. Accordingly, vanepumps are used in a variety of industries such as machine tools,production and material handling equipment and construction equipment.

Typically, since vane pumps are a form of variable displacement pumps,the vane pumps use a compensator as a pressure regulator. A compensatorchanges the displacement of the pump to match the flow systemrequirement by controlling the pressure. In other words, variable flowis achieved at a constant pressure setting. The compensator sensesdownstream pressure and adjusts the displacement to meet the desiredflow of the system.

Current vane pumps use two traditional compensators: a spring loadedcompensator and a hydraulic compensator. In a spring loaded compensator,a spring assembly connects the pressure ring which surrounds the rotorand vanes and applies a force to the pressure ring. Thus, the springassembly biases between the pump housing and the pressure ring to createa variable pressure around the rotor and vanes. Based on the springassembly characteristics such as the spring constant, the number ofcoils and material composition of the coils, the spring compensatorvaries the pump output displacement. Typically, the spring constantdetermines the pressure of the pump. Thus, to create variable flow whilemaintaining constant pressure, the spring compensator is designed withspecific criteria for the desired output.

A problem with spring compensators, however, is the existence of apressure limit. Coil spring compensators do not perform at highpressures, such as pressures exceeding 2,000 pounds per square inch(psi). To withstand high pressures, a coil spring compensator wouldrequire a burdensome number of coils. The required coils for pressuresexceeding 2,000 psi would require a spring housing extending off thepump body at a distance exceeding twelve inches. This extended housingprohibits the vane pump from being used in typical applications becauseof space constraints of a typical vane pump installation. The springcompensator also applies concentrated loading which leads to increasedwear of the springs and ring. Furthermore, the extended spring housingis unwieldy, leading to increased labor installation. Additionally, theextended spring housing results in increased manufacturing costs. Assuch, the spring compensator is not economically viable for high pumppressures such as pressures exceeding 2,000 psi.

In a hydraulic compensator, a valve system uses a piston assembly tosense the system pressure. To vary the flow and to compensate thepressure against the housing, the valve system opens and closes to movethe piston assembly against the housing. A problem with hydrauliccompensators, however, is contamination. Since the hydraulic compensatorrequires numerous components comprising the valve and piston assembly,those components are susceptible to failure and fluid leakage.Additionally, the hydraulic compensator requires constant maintenance tocheck on the valve system, leading to increased maintenance costs.

Efficient and economic pump systems are crucial for fluid systems. Assuch, fluid systems require pumps which can withstand high pressureswhile providing efficient output. Additionally, fluid systems requireminimal pump noise due to government regulations to limit noise onassembly/factory floors. Accordingly, a need exists for a pressurecompensated variable pump that can deliver high fluid pressures. A needalso exists for a pressure compensated variable pump that is compact indesign. The solution, however, must be a vane type pump having low noiseoutput. A need also exists for a pressured compensated variable pumpthat is easy to install. The solution, however, must minimizecontamination and maintenance procedures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates in an isometric view an embodiment of the fluid pumpdevice.

FIG. 2 illustrates in a cross sectional view an embodiment of the fluidpump device.

FIGS. 3 a and 3 b illustrate, in a top and side view, pressure elementsof the device.

FIG. 4 illustrates in a cut away view of an embodiment of the fluid pumpdevice.

FIG. 5 illustrates in a side view of the pressure elements of the fluidpump device.

FIG. 6 illustrates a cross sectional view of an embodiment of the fluidpump device with the pressure ring in a first position.

FIG. 7 illustrates a cross sectional view of an embodiment of the fluidpump device of FIG. 6, showing the pressure ring in a second position.

SUMMARY OF THE INVENTION

The present disclosure relates to a fluid pump. In particular, thepresent invention relates to a pressure compensated variabledisplacement pump which can operate at high fluid pressures. In anembodiment, the disclosure comprises a pump vane assembly positionedwithin a housing and a pressure ring positioned around the vane assemblyand floating within the housing. Additionally, the embodiment comprisesa compensator comprising a guide, a first end, a second end and aplurality of individual adjusting elements. The first end of thecompensator adjustably bears against the housing. The second end of thecompensator is in contact with the pressure ring, wherein each of theplurality of adjusting elements is positioned adjacent to one another,in series and in contact with the pressure ring via guide shoe to varythe pressure created by the vane assembly against the pressure ring.

The present disclosure also includes a method of varying pressurecomprising rotating a vane assembly within a housing and applying highpressure from the vane assembly against a pressure ring. Next, themethod comprises varying the pressure by biasing a plurality ofadjusting elements to reciprocate a guide against the pressure ring.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

As stated, the present disclosure relates to a pump. In particular, thepresent invention relates to a pressure compensated variabledisplacement pump that can operate at high pressures. FIG. 1 illustratesin an isometric view an exemplary embodiment of the present inventiongenerally shown as 10. The present invention 10 comprises a pump 12having a housing 14, an inlet 16, an outlet 18 and a compensator 20. Thecompensator 20 is positioned on the top of the pump 12 but may bepositioned on other sides of the pump 12. As shown, the pump 12 andcompensator 20 are configured together in a compact design to minimizerequired installation space.

Turning to FIG. 2, the pump 12 is shown in a cross sectional view,wherein the pump 12 comprises a vane type pump. Accordingly, the pump 12includes a shaft 22 and vane assembly 23 positioned within the housing14 wherein the vane assembly 23 includes a plurality of vanes 24 whichreciprocate within slots 26 of the shaft 22. Depending on the cycleportion, the vanes 24 extend out beyond the circumference of the shaft22 varying amounts, as shown in the art.

A pressure ring 28, positioned within the body 14, has an internal shaftthat surrounds the shaft 22 and vanes 24 wherein the pressure ring 28floats within the body 14. To maintain the pressure ring 24 within thebody 14, the pump 12 includes a thrust screw assembly 30 which limitsthe movement of the pressure ring 28. The thrust assembly 30 includes athrust screw 32, a lock nut 34 and a thrust bearing 36. The thrust screw32 extends and retracts within lock nut 34 to position the thrustbearing 36 within the body 14 to contact the pressure ring 28. Thus, theamount of float of the pressure ring 28 within the body 14 is controlledby the stop assembly 30. A fixed stop 37 also assists in controlling theposition of the pressure ring 28. The pump 12 further includes a secondfixed stop 38 which primarily positions the ring 28 during assembly.

As shown in FIG. 2, the compensator 20 is positioned on and extendsthrough the body 14. The compensator 20 includes a compensator body 39,a compensator adjuster 40, a plurality of adjusting elements 42, a pivotplate 44, a bearing plate 46, a guide 48 and a guide shoe 50. The guide48 has a first end 52 positioned near the compensator adjuster 40 and asecond end 54 positioned near the guide shoe 50, wherein the guide 48 ishollow between the first end 52 and the second end 54. The plurality ofadjusting elements 42 are positioned around the guide 48 between thefirst end 52 and the second end 54. Additionally, the pivot plate 44 ispositioned between the first end 52 and the plurality of adjustingelements 42 while the bearing plate 46 is positioned between the secondend 54 and the plurality of adjusting elements 42. Further, the guideshoe 50 is attached to the second end 54 while contacting the bearingplate 46. The guide shoe 50 is sized and shaped to match an outercircumference portion 56 of the pressure ring 28, as will be discussed.

Turning to FIGS. 3 a and 3 b, one of the adjusting elements 42 of theillustrated embodiment is shown, wherein each adjusting element 42 has acenter 58 and an edge 60. The center 58 is positioned within an aperture62 while the edge 60 is positioned at an angle from the center 58.Accordingly, the adjusting element 42 has a convex side 64 and a concaveside 66. In an embodiment, the adjusting element 42 may comprise awasher such as a Belleville washer. The adjusting elements 42 are sizedand shaped to distribute pressure from the center 58 to the edge 60 in acontinuous arc pattern.

Turning to FIG. 4, the adjusting elements 42 are positioned in series.The series comprises a plurality of stacked sets of adjusting elements42, each set containing one adjustment element 42 having its side 66(FIG. 3 b) facing pivot plate 44 and the second adjusting element 42having side 66 (FIG. 3 b) face the bearing plate 46, thus forming amultiple cup-like stack having an inherent resilience. As shown in FIG.4, the adjusting elements 42 are individual elements aligned with eachother around the guide 48 between the first end 52 and the second end 54(FIG. 2). The pivot plate 44 is also shaped similar to the adjustingelements 42 such that the first or top most adjusting element 42 ispositioned near the pivot plate 44. The bearing plate 46, however, issized and shaped in a flat configuration.

Turning to FIG. 5, the adjusting elements 42 are shown aligned in aseries described above around the guide 48. In this alignment, theconvex sides 64 of adjacent adjusting elements 42 are in contact witheach other. Accordingly, the concave sides 66 of adjacent adjustingelements 42 are oppositely positioned with each other. As such, theconcave side 66 of the first adjusting element is positioned oppositeboth the pivot plate 44 and the bearing plate 46.

During use, the compensator 20 maintains a constant pressure pump whilematching flow displacement demands of the pump 12. Hydraulic forcescause the ring 28 to move against the guide shoe 50 wherein thismovement is restricted by the adjusting elements 42. Turning to FIGS. 6and 7, the plurality of adjusting elements 42 bias the guide shoe 50downward to reciprocate between a first position (FIG. 6) and a secondposition (FIG. 7) in tandem with the pressure ring 28.

Since the pressure ring 28 floats within the body 14 and the shaft 22rotates in a fixed position within the housing 14 and the fluid betweenvanes 24 applies a pressure to the internal surface 29 of pressure ring28, the pressure ring 28 may move in an axial direction and becomes moreor less separated from portions of shaft 22 during a portion of the pumpcycle. As the shaft 22 rotates, the vanes 24 extend out of the slots 26to pick up fluid from the inlet 16 (shown in FIG. 1). The vanes 24 thendisplace the fluid toward the outlet 18 (shown in FIG. 1) creating ahigh pressure fluid area 68 between the shaft 22 and the pressure ring28.

To adjust for the high pressure generated in the pump and to maintain aconstant fluid flow output, the adjusting elements 42 bias the guideshoe 50 against the pressure ring 28 as shown in FIGS. 6 and 7.Accordingly, the guide shoe 50 moves from the first position in FIG. 6to the second position of FIG. 7. Thus, the high pressure developed inarea 68 is distributed from the center 58 to the edge 60 of theadjusting elements 42 (FIG. 3 a). The adjusting elements 42, in turn,are sized, shaped and combined in a stack to compensate for pressuresexceeding 500 psi, which biases the guide shoe 50 in tandem against thepressure ring 28. In an embodiment, the adjusting elements 42 are sized,shaped and configured to compensate for pressures exceeding 2,000 psi.In an embodiment, the adjusting elements 42 are sized, shaped andconfigured to compensate pressures up to and including 3,200 psi.

In comparing FIGS. 6 and 7 during a cycle, the plurality of adjustingelements 42 bias the guide shoe 50 against the outer circumferencepressure ring 28 to compensate for the high pressure created by the vaneassembly 23. In this series configuration of elements 42, the convexsides 64 of adjacent adjusting elements 42 are in contact with eachother and the concave sides 66 of adjacent adjusting elements 42 areoppositely spaced apart and facing each other (see FIG. 5), theplurality of adjusting elements 42 maintain the bias force necessary tocompensate for high pressures in a stack of relatively short axialdimension. The plurality of adjusting elements 42 are sized and shapedto maintain a bias force up to and including 3,200 psi. Additionally,since the individual adjusting elements 42 are aligned in series aroundthe guide 48, the compensator 20 maintains a minimal extension beyondthe body 14. As such, the compensator 20 and the adjusting elements 42provide a compact vane pump which can withstand high pressures.

While the concepts of the present disclosure have been illustrated anddescribed in detail in the drawings and foregoing description, such anillustration and description is to be considered as exemplary and notrestrictive in character, it being understood that only the illustrativeembodiments have been shown and described and that all changes andmodifications that come within the spirit of the disclosure are desiredto be protected by the following claims.

1. A pump, comprising: a vane assembly, the vane assembly beingpositioned within a housing; a pressure ring, the pressure ring beingpositioned around the vane assembly to float within the housing; and acompensator, the compensator comprising a guide, a first end, a secondend and a plurality of individual adjusting elements, the second endbeing in contact with the pressure ring and the plurality of adjustingelements being positioned adjacent the second end of the compensator inseries to vary pressure created by the vane assembly against thepressure ring.
 2. The pump according to claim 1, wherein the vaneassembly delivers pressure up to and including 3,200 pounds per squareinch.
 3. The pump according to claim 1, wherein the compensator furthercomprises at least one pivot plate positioned between the first end andthe plurality of adjusting elements.
 4. The pump according to claim 1,wherein the compensator comprises at least one bearing plate positionedbetween the second end and the plurality of adjusting elements.
 5. Thepump according to claim 1, wherein the plurality of adjusting elementsare each disc shaped, wherein each adjusting element has a center and anedge.
 6. The pump according to claim 5, wherein each of the plurality ofadjusting elements is sized and shaped to distribute the pressure fromthe center to the edge.
 7. The pump according to claim 1, wherein eachadjusting element has a convex side and a concave side.
 8. The pumpaccording to claim 7, wherein the plurality of adjusting elements arepositioned in series such that the convex sides of adjacent adjustingmembers are in contact.
 9. The pump according to claim 7, wherein theplurality of adjusting elements are positioned in series such that theconcave sides of adjacent adjusting members are oppositely positioned.10. The pump according to claim 1, wherein the plurality of individualadjusting elements are configured to reciprocate the guide between afirst position and a second position against the pressure ring.
 11. Ahigh pressure rotational pump, comprising: a vane assembly, the vaneassembly being positioned within a housing; a pressure ring, thepressure ring being positioned around the vane assembly to float withinthe housing; a compensator, the compensator comprising a guide having afirst end and a second end, the second end being in contact with thepressure ring; and a plurality of adjusting elements, the plurality ofadjusting elements being positioned around the guide between the firstend and the second end in series, wherein the plurality of adjustingelements are positioned to reciprocate the guide between a firstposition and a second position in tandem with the pressure ring to varypressure created by the vane assembly against the pressure ring.
 12. Thehigh pressure pump rotational according to claim 11, wherein theplurality of adjusting elements are sized and shaped to vary thepressure up to and including 3,200 pounds per square inch.
 13. The highpressure pump rotational according to claim 11, wherein the compensatorcomprises at least one bearing plate positioned between the second endand the plurality of adjusting elements.
 14. The high pressure pumprotational according to claim 11, wherein the compensator furthercomprises at least one pivot plate positioned between the first end andthe plurality of adjusting elements.
 15. The high pressure pumprotational according to claim 11, wherein the plurality of adjustingelements are disc shaped to distribute the pressure in a continuous arcpattern.
 16. The high pressure pump rotational according to claim 11,wherein each adjusting element has a convex side and a concave side. 17.The high pressure pump rotational according to claim 16, wherein theplurality of adjusting elements are positioned in series such that theconvex sides of adjacent adjusting members are in contact.
 18. The highpressure pump rotational according to claim 16, wherein the plurality ofadjusting elements are positioned in series such that the concave sidesof adjacent adjusting elements are oppositely positioned.
 19. A methodof varying pressure, comprising the steps: rotating a vane assemblywithin a pump housing; applying up to 3,200 pounds per square inchpressure from the vane assembly against a pressure ring; varying thepressure by biasing a plurality of adjusting elements to reciprocate aguide against the pressure ring.
 20. The method of varying pressureaccording to claim 19, further comprising the step of reciprocating theguide between a first position and a second position in tandem with thepressure ring.
 21. The method of varying pressure according to claim 20,further comprising the step of aligning the plurality of adjustingelements in series wherein convex sides of adjacent adjusting elementsare in contact.
 22. The method of varying pressure according to claim19, further comprising the step of aligning the plurality of adjustingelements in series wherein concave sides of adjacent adjusting elementsare oppositely positioned.